Image acquisition device and image acquisition method

ABSTRACT

An image acquisition device includes a spatial light modulator modulating irradiation light, a control unit controlling a modulating pattern so that a plurality of light converging points are formed in an observation object, a light converging optical system converging the modulated irradiation light, a scanning unit scanning positions of the plurality of light converging points in the observation object in a scanning direction intersecting an optical axis of the light converging optical system, and a photodetector configured to detect a plurality of observation lights generated from the plurality of light converging points. The control unit sets a center spacing between adjacent light converging points on the basis of the positions of the plurality of light converging points in a direction of the optical axis.

TECHNICAL FIELD

An aspect of the present invention relates to an image acquisitiondevice and an image acquisition method.

BACKGROUND ART

Non-Patent Literature 1 discloses a multiphoton absorption microscopeusing a spatial light modulator (SLM). This microscope is intended toacquire a fluorescence image from within an observation object at highspeed and clearly by forming and scanning a plurality of excitationlight spots using the SLM.

CITATION LIST Patent Literature

[Patent Literature 1] Japanese Unexamined Patent Publication No.2012-226268

Non Patent Literature

[Non-Patent Literature 1] Wan Qin, Yonghong Shao, Honghai Liu, XiangPeng, Hanben Niu, and Bruce Gao, “Addressable discrete-line-scanningmultiphoton microscopy based on spatial light modulator”, OPTICSLETTERS, Vol. 37, No. 5, pp. 827-829, Mar. 1, 2012

Because a plurality of portions can be simultaneously observed bysimultaneously radiating light to a plurality of positions of anobservation object in microscopic observation, there an advantage inthat it is possible to shorten an observation time and acquire states ofa plurality of portions at the same time. Because of this, it isnecessary to simultaneously radiate light to a plurality of positionsand simultaneously detect the observation light generated from thesepositions using a photodetector having, for example, a plurality ofdetection areas. However, when the observation light is detected in thismanner, the following problems may occur.

When the irradiation light is radiated to the observation object,aberration (for example, spherical aberration) caused by the surfaceshape of the observation object occurs. In order to correct suchaberration, it is preferable to control the wavefront of the irradiationlight using, for example, an SLM. However, it is difficult to performsuch correction for the observation light generated from the observationobject in many cases. Accordingly, the mode of the observation lightreaching the photodetector is affected by the aberration. That is,observation light generated at a deep position in the observation objecthas a larger light diameter at the time of arrival at the objective lensthan observation light generated at a shallow position in theobservation object. Accordingly, likewise, also in the photodetector,the light diameter of the observation light generated at a deep positionis larger than the light diameter of the observation light generated ata shallow position.

In microscopic observation, when a thick observation object is observedfrom a shallow position to a deep position, the light diameter of theobservation light differs according to an observation depth due to theabove-described phenomenon. Accordingly, when a plurality of observationlights generated from a plurality of positions are simultaneouslydetected, adjacent observation lights overlap each other in thephotodetector according to the observation depth and crosstalk mayoccur. When crosstalk occurs, it becomes difficult to accurately detecteach of the plurality of observation lights.

An aspect of the present invention is to provide an image acquisitiondevice and an image acquisition method capable of reducing crosstalk dueto overlapping of a plurality of observation lights.

Solution to Problem

An image acquisition device according to an embodiment of the presentinvention is a device for acquiring an image of an observation objectincluding: a spatial light modulator modulating irradiation light outputfrom a light source; a control unit controlling a modulating pattern tobe presented on the spatial light modulator so that a plurality of lightconverging points are formed in an observation object; a lightconverging optical system converging the modulated irradiation light sothat the plurality of light converging points are formed in theobservation object; a scanning unit scanning positions of the pluralityof light converging points in the observation object in a scanningdirection intersecting an optical axis of the light converging opticalsystem; a photodetector detecting a plurality of observation lightsgenerated from the plurality of light converging points; and an imagecreating unit creating an image of the observation object using adetection signal from the photodetector. The control unit sets a centerspacing between adjacent light converging points on the basis of thepositions of the plurality of light converging points in a direction ofthe optical axis.

Also, an image acquisition device according to another embodiment of thepresent invention is a device for acquiring an image of an observationobject including: a spatial light modulator modulating irradiation lightoutput from a light source; a control unit controlling a modulatingpattern to be presented on the spatial light modulator so that aplurality of light converging points are formed in an observationobject; a light converging optical system converging the modulatedirradiation light so that the plurality of light converging points areformed in the observation object; a photodetector detecting a pluralityof observation lights generated from the plurality of light convergingpoints; and an image creating unit creating an image of the observationobject using a detection signal from the photodetector. The modulatingpattern includes a pattern for scanning the plurality of lightconverging points in a scanning direction intersecting an optical axisof the irradiation light. The control unit sets a center spacing betweenadjacent light converging points on the basis of positions of theplurality of light converging points in a direction of the optical axis.

Also, an image acquisition method according to an embodiment of thepresent invention is a method of acquiring an image of an observationobject, the method including the steps of: presenting a modulatingpattern for forming a plurality of light converging points in anobservation object on a spatial light modulator; modulating irradiationlight output from a light source in the spatial light modulator andconverging the modulated irradiation light by a light converging opticalsystem so that the plurality of light converging points are formed inthe observation object; detecting a plurality of observation lightsgenerated from the plurality of light converging points while scanningpositions of the plurality of light converging points in the observationobject in a scanning direction intersecting an optical axis of theirradiation light; and creating an image of the observation object usinga detection signal obtained in the light detecting step. A centerspacing between adjacent light converging points is set on the basis ofthe positions of the plurality of light converging points in a directionof the optical axis in the pattern presenting step.

In the image acquisition device and the image acquisition method, it ispossible to simultaneously and easily form a plurality of lightconverging points by presenting a modulating pattern on the spatiallight modulator. Then, the plurality of light converging points arescanned and the plurality of observation lights generated from theplurality of light converging points are detected. In this manner,according to the image acquisition device and the image acquisitionmethod described above, it is possible to simultaneously radiate aplurality of lights to the observation object and further simultaneouslydetect a plurality of observation lights. Accordingly, it is possible toshorten an observation time and easily acquire states of a plurality ofportions at the same time.

Also, when the plurality of observation lights generated from theplurality of positions are simultaneously detected as described above,adjacent observation lights overlap each other in the photodetectoraccording to the observation depth and crosstalk may occur. On the otherhand, in the image acquisition device and the image acquisition methoddescribed above, a center spacing between adjacent light convergingpoints is set on the basis of the positions of the plurality of lightconverging points in the direction of the optical axis (that is, theobservation depth). Thereby, for example, because it is possible towiden the center spacing between adjacent light converging points whenthe light diameter of the observation light increases in thephotodetector, it is possible to prevent a plurality of observationlights from overlapping one another and reduce crosstalk. Accordingly,it is possible to accurately detect each of the plurality of observationlights and provide a clear image of the observation object.

Also, in the above-described image acquisition device, the control unitmay change the center spacing according to a change in the positions ofthe plurality of light converging points in the direction of the opticalaxis. Likewise, the center spacing may be changed according to a changein the positions of the plurality of light converging points in thedirection of the optical axis in the pattern presenting step of theimage acquisition method. Thereby, it is possible to continuouslyperform observation of a plurality of depths while suppressingcrosstalk. In this case, the control unit increases the center spacingas the positions of the plurality of light converging points in thedirection of the optical axis are distanced further from a surface ofthe observation object (or in the pattern presenting step). Thereby, itis possible to suitably reduce crosstalk of the observation light due toaberration of a surface of the observation object.

Also, in the above-described image acquisition device, the scanning unitmay include a light scanner receiving the modulated irradiation light orinclude a stage moving the observation object in the scanning directionwhile holding the observation object. Also, in the light detecting stepof the above-described image acquisition method, scanning of theplurality of light converging points may be performed using a lightscanner receiving the modulated irradiation light, scanning of theplurality of light converging points may be performed using a stagemoving the observation object in the scanning direction while holdingthe observation object, or a pattern for scanning the plurality of lightconverging points may be superimposed on the modulating pattern.According to any one thereof, it is possible to suitably scan positionsof the plurality of light converging points.

Also, in the above-described image acquisition device, the photodetectormay have a plurality of detection areas for detecting the plurality ofobservation lights and sizes of the plurality of detection areas and acenter spacing between the detection areas may be set on the basis ofthe positions of the plurality of light converging points in thedirection of the optical axis. Likewise, in the light detecting step ofthe above-described image acquisition method, a photodetector having aplurality of detection areas for detecting the plurality of observationlights may be used and the plurality of detection areas may be set onthe basis of the positions of the plurality of light converging pointsin the direction of the optical axis. Thereby, because a pitch betweenand sizes of the plurality of detection areas are set according to acenter spacing between observation lights and/or the light diameter, itis possible to suitably detect a plurality of observation lights.

Also, in the above-described image acquisition device, the photodetectormay output a plurality of image data corresponding to the plurality ofdetection areas as the detection signal and the image creating unit maycombine the plurality of image data to create the image of theobservation object. Likewise, in the above-described image acquisitionmethod, the photodetector may output a plurality of image datacorresponding to the plurality of detection areas as the detectionsignal, and the plurality of image data may be combined to create animage of the observation object in the image creating step. Thereby,because it is possible to divide an area to be observed in theobservation object into a plurality of areas and create images of theareas in parallel, an observation time can be effectively shortened.

Also, in the above-described image acquisition device, the photodetectormay include a multi-anode photomultiplier tube having a plurality ofanodes or include an area image sensor having a plurality of pixels.Likewise, in the light detecting step of the above-described imageacquisition method, the plurality of the observation lights may bedetected using a multi-anode photomultiplier tube having a plurality ofanodes and the plurality of the observation lights may be detected usingan area image sensor having a plurality of pixels. According to any onethereof, it is possible to accurately detect a plurality of observationlights.

Also, in the above-described image acquisition device and imageacquisition method, the plurality of light converging points may bearranged in a direction intersecting the scanning direction when viewedfrom the direction of the optical axis. Thereby, because it is possibleto divide an area to be observed in the observation object into aplurality of areas and create images of the areas in parallel, anobservation time can be effectively shortened.

Also, the control unit may further set the center spacing betweenadjacent light converging points on the basis of an amount of aberrationof a plurality of light converging points in a direction of an opticalaxis. Likewise, in the pattern presenting step of the above-describedimage acquisition method, the center spacing between adjacent lightconverging points may be further set on the basis of amounts ofaberration of a plurality of light converging points in a direction ofthe optical axis. Thereby, it is possible to suitably reduce thecrosstalk of the observation light due to aberration in the observationobject.

Advantageous Effects of Invention

According to an image acquisition device and an image acquisition methodaccording to aspects of the present invention, it is possible tosimultaneously radiate a plurality of lights for which light convergingpositions are different in a depth direction of an observation object.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a configuration of an image acquisitiondevice according to an embodiment of the present invention.

FIG. 2 is a diagram conceptually illustrating states of irradiationlight on an observation object and its vicinity.

FIG. 3 is a diagram conceptually illustrating states of irradiationlight on an observation object and its vicinity.

FIG. 4 is a diagram schematically illustrating an example of anarrangement direction of light converging points viewed from an opticalaxis direction of an objective lens.

FIG. 5 is a front view illustrating a light detecting surface of aphotodetector.

FIG. 6 is a diagram conceptually illustrating a plurality of image dataincluded in a detection signal.

FIG. 7 is a flowchart of an image acquisition method.

FIG. 8 is a diagram conceptually illustrating a state in which areference height is set.

FIG. 9 is a diagram illustrating a state in which an observation depthof a light converging point is set.

FIG. 10 is a diagram illustrating a state in which adjacent point imagesoverlap in the photodetector and crosstalk occurs.

FIG. 11 is a flowchart of an image acquisition method according to afirst modified example.

FIG. 12 illustrates an image acquired in an example.

FIG. 13 illustrates an image acquired in an example.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of an image acquisition device and an imageacquisition method according to aspects of the present invention will bedescribed in detail with reference to the accompanying drawings. Thesame elements are denoted by the same reference signs in the descriptionof the drawings, and redundant description thereof will be omitted.

FIG. 1 is a diagram illustrating a configuration of an image acquisitiondevice 1A according to an embodiment of the present invention. The imageacquisition device 1A is a device for radiating irradiation light L1 toan observation object B and observing observation light (detected light)L2 generated in the observation object B by the irradiation light L1.The image acquisition device 1A is, for example, a microscope device. Asthe microscope device, for example, an upright microscope or an invertedmicroscope can be included. The observation light L2 is, for example,fluorescence, phosphorescence, high-frequency generated light (SHG),reflected light, transmitted light, scattered light, or the like. Asillustrated in FIG. 1, the image acquisition device 1A includes anirradiation light generating unit 10, a scanning unit 20, a irradiationoptical unit 30, an observation unit 40, and a control unit 50.

The irradiation light generating unit 10 generates the irradiation lightL1 to be radiated to the observation object B. The irradiation lightgenerating unit 10 of the present embodiment includes a light source 11,a beam expander 12, and a spatial light modulator (SLM) 13.

The light source 11 outputs irradiation light L0. The irradiation lightL0 includes, for example, light having a wavelength to be radiated tothe observation object B. The light source 11 is configured to include,for example, a laser light source which oscillates pulsed light orcontinuous wave, an SLD light source, an LED light source, or the like.The beam expander 12 includes, for example, a plurality of lenses 12 aand 12 b arranged side by side on the optical axis of the irradiationlight L0, and adjusts the size of a cross section perpendicular to theoptical axis of the irradiation light L0. Also, the lenses 12 a and 12 bmay be convex lenses, concave lenses, or combinations thereof.

The spatial light modulator 13 is optically coupled to the light source11 and modulates the irradiation light L0 from the light source 11,thereby generating the irradiation light L1 to be radiated to theobservation object B. The spatial light modulator 13 has a plurality ofpixels arranged two-dimensionally, and modulates an intensity or phaseof the irradiation light L0 output from the light source 11 for each ofa plurality of pixel columns. The modulating pattern (hologram) to bepresented on the spatial light modulator 13 is controlled by the controlunit 50 to be described below. The spatial light modulator 13 may be ofa phase modulation type or an amplitude (intensity) modulation type.Also, the spatial light modulator 13 may be either a reflection type ora transmission type. Also, a plurality of spatial light modulators 13may be provided. In this case, the irradiation light L0 is modulated aplurality of times.

The scanning unit 20 is an example of a scanning unit in the presentembodiment. The scanning unit 20 has a light scanner 21 as a scanningoptical system. The light scanner 21 is optically coupled to the spatiallight modulator 13, and receives the irradiation light L1 modulated bythe spatial light modulator 13. Also, the light scanner 21 scans anirradiation position of the irradiation light L1 on the observationobject B. Further, the light scanner 21 receives the observation lightL2 generated at the light converging point of the observation object B.Thereby, the observation light L2 is de-scanned. The light scanner 21 iscontrolled by the control unit 50 to be described below. The lightscanner 21 includes, for example, a galvanometer mirror, a resonancemirror, an MEMS mirror, a two-dimensional acousto-optic element (AOM), apolygon mirror, or the like. When the light scanner 21 is a biaxialscanner, the light scanner 21 may include an image transferring opticalsystem such as a telecentric optical system.

In addition to the light scanner 21, the scanning unit 20 may furtherinclude a mirror 22. The mirror 22 bends an optical axis of theirradiation light L1 to optically couple the light scanner 21 and theirradiation optical unit 30.

The irradiation optical unit 30 irradiates the observation object B withthe irradiation light L1 provided from the scanning unit 20 and outputsthe observation light L2 from the observation object B to theobservation unit 40. The irradiation optical unit 30 includes a stage31, an objective lens 32, an objective lens moving mechanism 33, and areflection mirror 34. A dichroic mirror may be used as the reflectionmirror 34.

The stage 31 is a member for supporting the observation object B (or acontainer such as a glass slide, a Petri dish, a microplate, a glassbottomed dish, or the like that contains the observation object B). Thestage 31 is made of, for example, glass. In the example illustrated inFIG. 1, the irradiation light L1 is radiated from a front side of thestage 31, but the irradiation light L1 may be radiated from a back sideof the stage 31 to the observation object B through the stage 31. Thestage 31 can move in a plane direction intersecting (for example,orthogonal to) the optical axis of the objective lens 32 to be describedbelow, while holding the observation object B. Also, the stage 31 may bemovable in the optical axis direction of the objective lens 32.

The objective lens 32 is arranged to face the observation object B andis a light converging optical system that forms a light converging pointof the irradiation light L1 inside the observation object B. Also, theobjective lens 32 receives the observation light L2 generated at thelight converging point of the observation object B and collimates theobservation light L2. An objective lens for the irradiation light L1 andan objective lens for the observation light L2 may be providedseparately. For example, an objective lens having a high numericalaperture (NA) may be used for the irradiation light L1, and theobjective lens may locally converge light through aberration correctionby the spatial light modulator 13. Also, more light can be extractedusing an objective lens with a large pupil for the observation light L2.The objective lens for the irradiation light L1 and the objective lensfor the observation light L2 are arranged to sandwich the observationobject B and the transmitted light on the observation object B of theirradiation light L1 may be acquired as the observation light L2.

The objective lens moving mechanism 33 is a mechanism for moving theobjective lens 32 in the optical axis direction of the irradiation lightL1. The objective lens moving mechanism 33 includes, for example, astepping motor or a piezoelectric actuator.

The reflection mirror 34 reflects the irradiation light L1 reaching theirradiation optical unit 30 from the irradiation light generating unit10 toward the objective lens 32. Also, the reflection mirror 34 reflectsthe observation light L2 from the observation object B toward thescanning unit 20.

When a distance between the objective lens 32 and the spatial lightmodulator 13 is long, at least one telocentric optical system may beprovided on the optical axis of the irradiation light L1 and theobservation light L2. As an example, FIG. 1 illustrates two telecentricoptical systems 61 and 62. The telecentric optical systems 61 and 62serve to transfer the wavefront of the irradiation light L1 generated inthe spatial light modulator 13 to a rear focal point of the objectivelens 32. The telecentric optical systems 61 and 62 may be double-sidedtelecentric optical systems. In this case, the telecentric opticalsystem 61 arranged between the spatial light modulator 13 and the lightscanner 21 is adjusted to form an image on a modulation surface of thespatial light modulator 13 and a scanning surface of the light scanner21. The telecentric optical system 62 arranged between the light scanner21 and the objective lens 32 is adjusted to form an image on thescanning surface of the light scanner 21 and the pupil surface of theobjective lens 32. Also, if the wavefront of the irradiation light L1generated by the spatial light modulator 13 can be transferred to therear focal point of the objective lens 32, the telecentric opticalsystems 61 and 62 may be an image-side telecentric optical system or anobject-side telecentric optical system. Also, when the distance betweenthe objective lens 32 and the spatial light modulator 13 is extremelysmall, it is also possible to omit the telecentric optical system.

The observation unit 40 has a photodetector 41, a filter 42, and aconverging lens 43. The photodetector 41 is optically coupled to theobjective lens 32 and the light scanner 21 and receives the observationlight L2 to detect a light intensity of the observation light L2. Thephotodetector 41 is optically coupled to the light scanner 21 via adichroic mirror 14 provided in the irradiation light generating unit 10.The dichroic mirror 14 is arranged at a position at which theirradiation light L1 modulated by the spatial light modulator 13 and theobservation light L2 de-scanned by the light scanner 21 are received,transmits at least a part of the irradiation light L1, and reflects atleast a part of the observation light L2. The photodetector 41 detectsthe light intensity of the observation light L2 and outputs a detectionsignal Sd. The photodetector 41 may include a multi-anode typephotomultiplier tube (PMT) having a plurality of anodes, a photodiodearray in which a plurality of photodiodes are configured to be arrangedin an array shape, or an avalanche photodiode array in which a pluralityof avalanche photodiodes are arranged in an array shape. Alternatively,the photodetector 41 may be an area image sensor having a plurality ofpixels such as a CCD image sensor, an EM-CCD image sensor, or a CMOSimage sensor or may be a line sensor. In particular, the multi-anodetype PMT has a high multiplication factor and has a larger lightreceiving surface than the others.

The filter 42 is arranged on the optical axis between the dichroicmirror 14 and the photodetector 41. The filter 42 cuts out wavelengthsof the irradiation light L1 and wavelengths of fluorescence or the likeunnecessary for observation from light incident on the photodetector 41.The converging lens 43 is arranged immediately in front of thephotodetector 41 and converges the observation light L2 toward thephotodetector 41. Also, the filter 42 may be arranged at either thefront stage or the rear stage of the converging lens 43. Also, when thefilter 42 is unnecessary, it is unnecessary to provide the filter 42.

The control unit 50 controls the irradiation light generating unit 10,the scanning unit 20, and the irradiation optical unit 30. For example,the control unit 50 controls the light source 11, the spatial lightmodulator 13, and the light scanner 21. Also, for example, the controlunit 50 controls the position (height) of the objective lens 32 in theoptical axis direction using the objective lens moving mechanism 33.Also, for example, the control unit 50 moves the stage 31 which supportsthe observation object B in a direction intersecting the optical axisdirection. The control unit 50 is configured to include an input device51 such as a mouse and a keyboard, a display device 52 such as adisplay, and a computer 53.

Also, the computer 53 is an example of an image creating unit accordingto this embodiment. The computer 53 is a personal computer, a smartdevice or the like and includes an image processing circuit (imageprocessing processor), a control circuit (control processor), and aninternal memory. The computer 53 creates an image of the observationobject B using the detection signal Sd from the photodetector 41 andlight irradiation position information in the light scanner 21. Thecreated image is displayed on the display device 52. Also, the computer53 is an example of a control unit (controller) in the presentembodiment. The computer 53 controls a modulating pattern (hologram) tobe presented on the spatial light modulator 13 so that a desired lightconverging point is formed in the observation object B. The computer 53controls a modulation amount of intensity or phase for each of aplurality of pixels of the spatial light modulator 13 by controlling themodulating pattern to be presented on the spatial light modulator 13.The created image may be stored in the memory of the computer 53 or theexternal storage device.

Here, the aspect of the light converging point of the observation objectB will be described in detail. FIGS. 2 and 3 are diagrams conceptuallyillustrating states of irradiation light L1 in the observation object Band its vicinity. As illustrated in FIGS. 2 and 3, in the presentembodiment, the irradiation light L1 is converged on a plurality oflight converging points P1 by the objective lens 32. When the number oflight converging points is three or more, FIGS. 2 and 3 illustrate twoadjacent light converging points P1 of the plurality of light convergingpoints P1 in an enlarged manner. A virtual line A1 in FIGS. 2 and 3 is areference line representing a reference height of the objective lens 32.

The position of the light converging points P1 in the optical axisdirection of the objective lens 32 (in other words, the depth directionof the observation object B) is different between FIGS. 2 and 3. Thatis, a case in which the depth d of the light converging points P1 fromthe surface of the observation object B is shallow is illustrated inFIG. 2 and a case in which the depth d of the light converging points P1from the surface of the observation object B is deep is illustrated inFIG. 3. In other words, the light converging points P1 illustrated inFIG. 3 are further away from the surface of the observation object Bthan the light converging points P1 illustrated in FIG. 2.

The center spacing between the light converging points P1 in thedirection orthogonal to the optical axis direction of the objective lens32 is set on the basis of positions of the light converging points P1 inthe optical axis direction of the objective lens 32. For example, asillustrated in FIG. 2, when the depth d of the light converging pointsP1 is shallow, the computer 53 sets the center spacing W betweenadjacent light converging points P1 to a narrow distance. Also, asillustrated in FIG. 3, when the depth d of the light converging pointsP1 is deep, the computer 53 sets the center spacing W between adjacentlight converging points Pt to a wide distance. As described above, thecomputer 53 sets the center spacing between adjacent light convergingpoints P1 to a wider distance as the position of the light convergingpoints P1 in the optical axis direction of the objective lens 32 isdistanced further from the surface of the observation object B. Suchsetting is performed through control of the modulating pattern to bepresented on the spatial light modulator 13. Also, the computer 53changes the center spacing W between adjacent light converging points P1each time in correspondence with a change in an observation depth d,i.e., a change in the position of the light converging points P1 in theoptical axis direction of the objective lens 32.

Also, the center spacing between the light converging points P1 in thedirection orthogonal to the optical axis direction of the objective lens32 is further set on the basis of amounts of aberration on the surfaceand/or the inside of the observation object B. For example, the centerspacing between the light converging points P1 is set to be wide whenthe amount of aberration is large and the center spacing between thelight converging points P2 is set to be narrow when the amount ofaberration is small. Such setting is performed through control of themodulating pattern to be presented on the spatial light modulator 13.Also, the amounts of aberration on the surface and/or the inside of theobservation object B may be actually measured or obtained or may beestimated and obtained through simulation or the like.

FIG. 4 is a diagram schematically illustrating an example of thearrangement direction of the light converging points P1 viewed from theoptical axis direction of the objective lens 32. FIG. 4(a) illustrates ascanning direction A2 of the light converging points P1 and FIG. 4(b)illustrates a state in which the light converging points P1 is scannedby the light scanner 21 viewed from the optical axis direction of theirradiation light L1. As illustrated in FIG. 4(a), in this example, whenviewed from the optical axis direction of the irradiation light L1, thelight converging points P1 are arranged in a direction A3 intersectingthe scanning direction A2. Also, as illustrated in FIG. 4(b), there area high-speed axis and a low-speed axis for scanning by the light scanner21 and an operation in which the light converging point P1 is movedalong the high-speed axis, shifted in a direction of the low-speed axis,and then moved again along the high-speed axis is iterated. In thisexample, the arrangement direction of the light converging points P1viewed from the optical axis direction of the irradiation light L1 isalong the low-speed axis (i.e., the axis intersecting the scanningdirection A2). A direction A3 is orthogonal to the scanning direction A2or inclined with respect to the scanning direction A2. Also, the lightscanner 21 may scan the light converging point P1 so that the lightconverging point P1 also moves in the low-speed axis direction whilemoving along the high-speed axis. Also, not only line scanning but alsotiling scanning may be used.

The plurality of light converging points P1 formed with theabove-described positional relationship are implemented by the computer53 for controlling the modulating pattern to be presented on the spatiallight modulator 13 and the objective lens 32. The computer 53 controlsthe modulating pattern so that a plurality of light converging points P1are formed in the observation object B. Then, the modulated irradiationlight L1 is converged by the objective lens 32 and the plurality oflight converging points P1 are formed in the observation object B.

FIGS. 5(a) to 5(c) are front views illustrating a light detectingsurface 44 of the photodetector 41 of the present embodiment. Asillustrated in FIGS. 5(a) to 5(c), the light detecting surface 44includes a plurality of light detecting units 44 a. For example, whenthe photodetector 41 is a multi-anode PMT, the light detecting unit 44 acorresponds to each anode of the multi-anode PMT. Also, for example,when the photodetector 41 is an area image sensor, the light detectingunit 44 a corresponds to one pixel or pixel group. Also, for example,when the photodetector 41 is a photodiode array (line sensor), the lightdetecting unit 44 a corresponds to each photodiode.

As illustrated in FIGS. 5(a) to 5(c), point images P2 of a plurality ofobservation lights generated from a plurality of light converging pointsP1 are formed on the light detecting surface 44. The photodetector 41detects the plurality of observation lights by detecting lightintensities of a plurality of point images P2. FIG. 5(a) illustrates acase in which the observation depth of the light converging point P1 isshallow, FIG. 5(c) illustrates a case in which the observation depth ofthe light converging point P1 is deep, and FIG. 5(b) illustrates a casein which the observation depth of the light converging point P1 isintermediate between these observation depths. Because a distancebetween the surface of the observation object B that gives theaberration and the light converging point P1 (i.e., a distance insidethe observation object B) becomes longer when the observation depth ofthe light converging point P1 in the observation object B is deeper, thelight diameter of the point image P2 of the observation light reachingthe photodetector 41 increases. For example, in FIG. 5(a), because theobservation depth of the light converging point P1 is shallow, the lightdiameter of the point image P2 is small. In contrast, in FIG. 5(c),because the observation depth of the light converging point P1 is deep,the light diameter of the point image P2 is large. A size of the lightdiameter of the point image P2 of the observation light reaching thephotodetector 41 also differs according to a size of the distancebetween the focal point of the objective lens 32 and the lightconverging point P1.

The photodetector 41 has a plurality of detection areas 45 for detectinga plurality of point images P2. The plurality of detection areas 45 areindependent of each other and each includes one or more light detectingunits 44 a. In the present embodiment, the sizes of the plurality ofdetection areas 45 and the center spacing between the detection areas 45are set on the basis of positions of the plurality of light convergingpoints P1 (i.e., observation depths) in the optical axis direction ofthe objective lens 32.

Specifically, in the example illustrated in FIG. 5(a), because theobservation depth of the light converging point P1 is shallow, the sizesof the plurality of detection areas 45 are set to be small and thecenter spacing between the detection areas 45 is also set to be short.As an example, each detection area 45 is set to include one lightdetecting unit 44 a and the center spacing between the detection areas45 is set to be equal to the center spacing between the light detectingunits 44 a. In the example illustrated in FIG. 5(c), because theobservation depth of the light converging point P1 is deep, the sizes ofthe plurality of detection areas 45 are set to be larger than those inFIG. 5(a) and the center spacing between the detection areas 45 is alsoset to be longer than that in FIG. 5(a). As an example, each detectionarea 45 may be set to include three light detecting units 44 a, and thecenter spacing between the detection areas 45 may be set to be equal tothe center spacings between every fifth light detecting unit 44 a. Inthis case, detection signals from three light detecting units 44 a aresummed and a sum of the detection signals becomes the detection signalfrom the detection area 45. In the example illustrated in FIG. 5(b),because the observation depth of the light converging point P1 isintermediate between FIG. 5(a) and FIG. 5(c), the sizes of the pluralityof detection areas 45 are set to be larger than those in FIG. 5(a) andsmaller than those in FIG. 5(c), and the center spacing between thedetection areas 45 is set to be longer than that in FIG. 5(a) andshorter than that in FIG. 5(c). As an example, each detection area 45 isset to include two light detecting units 44 a, and the center spacingbetween the detection areas is set to be equal to the center spacingsbetween every second light detecting unit 44 a. In this case, thedetection signals from the two light detecting units 44 a are summed anda sum of the detection signals become a detection signal from thedetection area 45. In many cases, the center spacing between thedetection areas 45 becomes a value different from the center spacing Wbetween the light converging points P1.

The computer 53 serving as an image creating unit creates an image ofthe observation object B on the basis of a detection signal Sd from thephotodetector 41 and light irradiation position information in the lightscanner 21. The detection signal Sd from the photodetector 41 includes aplurality of image data corresponding to the plurality of detectionareas 45. FIG. 6 is a diagram conceptually illustrating a plurality ofimage data D1 included in the detection signal Sd. A plurality ofelongated image data (strip images) D1 are generated from the pluralityof observation light by scanning the plurality of light convergingpoints P1 on the observation object B in the above-described manner. Inother words, each piece of image data D1 is an image of the scanningarea of each light converging point P1. In FIG. 6, two of the pluralityof image data D1 are enlarged and illustrated. The computer 53 createsan image of the observation object B by mutually combining a pluralityof image data D1. Thereby, an internal image of the observation object Bat a desired observation depth can be created.

Also, each scanning area may be set so that the scanning areas ofadjacent light converging points P1 partially overlap. In this case, forexample, by combining a plurality of image data D1 while weightingoverlapping portions, a boundary portion between pieces of image data D1can be made inconspicuous.

Here, FIG. 7 is a flowchart illustrating the operation of the imageacquisition device 1A described above. The image acquisition methodaccording to the present embodiment will be described with reference toFIG. 7.

First, after the observation object B is placed on the stage 31, areference height of the objective lens 32 is set (step S1). In step S1,a distance between the objective lens 32 and the observation object B isadjusted by the objective lens moving mechanism 33 or the stage 31 andthe reference height is set. FIG. 8 is a diagram conceptuallyillustrating a state in which a reference height Z0 is set. For example,the height of the objective lens 32 may be adjusted so that the focalposition of the objective lens 32 is aligned with the surface of theobservation object B and a height thereof may be set as the referenceheight Z0. Also, by moving the stage 31 in the optical axis direction ofthe objective lens 32, the focal position of the objective lens 32 maybe aligned with the surface of the observation object B. The computer 53stores the reference height Z0.

Next, as illustrated in FIG. 9, the observation depth d of the lightconverging point P1, i.e., the depth inside the observation object B tobe imaged, is set (step S2). In this step S2, for example, the observermay input an optical axis direction position of the objective lens 32 tothe reference height Z0 or input a depth from the surface of theobservation object B, via the input device 51. The depth inside theobservation object B may be an actual distance or an optical distance.Also, in consideration of a refractive index of the medium (such as air,water, oil, glycerin, silicone, or the like) between the objective lens32 and the observation object B and/or the refractive index of theobservation object B, an amount by which the objective lens 32 (or thestage 31) is actually moved may be calculated. For example, in thiscase, when an observation depth d of the light converging point P1 is anoptical distance, a refractive index of the medium is set as n_(a), anda refractive index of the observation object B is set as n_(b), amovement amount of the objective lens 32 (or the stage 31) is calculatedas n_(b)·d/n_(a).

Subsequently, the center spacing W between the light converging pointsP1 is set (step S3). In step S3, as illustrated in FIGS. 2 and 3, it ispreferable to further increase the center spacing W when the depth d ofthe light converging point P1 becomes deeper. Also, for example, thecenter spacing W may be set on the basis of parameters such as thenumerical aperture (NA) of the objective lens 32, the refractive indexof the medium between the objective lens 32 and the observation objectB, the refractive index of the observation object B, the wavelength ofthe irradiation light L1, the surface shape and/or internal structure ofthe observation object B, and the amounts of aberration on the surfaceand/or the inside of the observation object B. These parameters may beobtained through actual measurement or may be estimated and obtainedthrough simulation or the like. Also, center spacings W corresponding todepths d may be calculated in advance and stored as a table in a storagearea of the computer 53, and an appropriate center spacing W may beselected from the storage area.

Subsequently, a modulating pattern (hologram) is created (step S4). Inthis step S4, a computer generated hologram (CGH) to be presented on thespatial light modulator 13 is created on the basis of spacing W betweenthe light converging points P1 and depths d thereof set in theabove-described steps S2 and S3. This step S4 is performed by, forexample, the computer 53. Alternatively, CGHs corresponding to thedepths d and the spacing W may be calculated in advance and stored as atable in a storage means inside the computer 53, and an appropriate CGHmay be selected from among the CGHs.

Subsequently, the CGH created in step S4, i.e., a modulating pattern inwhich a plurality of light converging points P1 are formed in theobservation object B, is presented on the spatial light modulator 13(pattern presenting step S5). Then, the irradiation light L0 output fromthe light source 11 is modulated in the spatial light modulator 13, andthe modulated irradiation light L1 is converged by the objective lens32, so that the plurality of light converging points P1 are formed atthe depth d of the observation object B (light converging point formingstep S6). In steps S5 and S6, the distance between the objective lens 32and the observation object B is adjusted so that the light convergingpoint P1 is formed at the depth d inside the observation object B. Inthis state, the CGH is presented on the spatial light modulator 13, sothat the irradiation light L0 output from the light source 11 ismodulated, the modulated irradiation light L1 is concentrated by theobjective lens 32, and the plurality of light converging points P1 atthe position of the depth d inside the observation object B are formedwith the spacing W. Also, after the distance between the objective lens32 and the observation object B is adjusted, the CGH may be presented onthe spatial light modulator 13 and the modulated irradiation light L1may be converged by the objective lens 32.

Subsequently, scanning and light detection of the plurality of lightconverging points P1 are performed (light detecting step S7). In thislight detecting step S7, while the positions of the plurality of lightconverging points P1 inside the observation object B are scanned in thescanning direction intersecting the optical axis of the irradiationlight L1, the observation light L2 generated from the plurality of lightconverging points P1 is detected. At this time, because a plurality ofobservation lights L2 are de-scanned by the light scanner 21, it ispossible to fixedly detect the position of the point image P2 of theobservation light L2 in the photodetector 41 while moving the lightconverging point P1. From the photodetector 41, a detection signal Sdincluding a plurality of image data corresponding to a plurality ofpoint images P2 is output to the computer 53.

Subsequently, an image of the observation object B is created (imagecreating step S8). In this image creating step S8, an image of theobservation object B is created by the computer 53 using the detectionsignal Sd (light intensity information) obtained in the light detectingstep S7 and the optical scanning position information from the lightscanner 21. Specifically, as illustrated in FIG. 6, a plurality of imagedata D1 are acquired from the detection signal Sd and the light scanningposition information (step S8 a) and the image of the observation objectB is created by mutually combining the plurality of image data D1 (stepS8 b).

Effects of the image acquisition device 1A and the image acquisitionmethod of the present embodiment described above will be described. Inthe image acquisition device 1A and the image acquisition method of thepresent embodiment, the modulating pattern is presented on the spatiallight modulator 13, so that it is possible to simultaneously and easilyform the plurality of light converging points P1. Then, the plurality oflight converging points P1 are scanned (scanned), and the point image P2of the plurality of observation lights generated at these lightconverging points P1 is detected by the photodetector 41. As describedabove, according to each of the image acquisition device 1A and theimage acquisition method of the present embodiment, it is possible tosimultaneously irradiate the observation object B with a plurality ofirradiation lights L1 and simultaneously detect a plurality ofobservation lights L2. Accordingly, it is possible to shorten theobservation time and easily acquire states of a plurality of portions atthe same time.

When the observation object B is, for example, a biological sample, theobservation time can be shortened, the load on a living body can bereduced, and observation in a better state becomes possible. Forexample, it is difficult to observe the living body in a living statewhen a time period of 100 minutes is required for three-dimensionalimaging, but observation is considered to be possible in the livingstate if the time period is 10 minutes.

Also, when a plurality of observation lights L2 generated from aplurality of positions are simultaneously detected, adjacent pointimages P2 overlap each other in the photodetector 41 according to theobservation depth d and crosstalk may occur. FIG. 10 is a diagramillustrating such a phenomenon. As illustrated in FIG. 10(a), a case inwhich point images P2 of a plurality of observation lights are incidenton a plurality of detection areas 45 at a certain observation depth d isconsidered. As described above, the light diameter of the observationlight generated at a deep position in the observation object B due tothe aberration at the surface of the observation object B is larger thanthe light diameter of the observation light generated at a shallowposition (see FIG. 5). Here, the aberration on the surface of theobservation object B includes, for example, spherical aberration causedby a refractive index difference between the immersion liquid or airused for observation and the observation object B, astigmatism occurringwhen a refractive index boundary is not perpendicular to the opticalaxis, coma aberration, defocus aberration, and the like. In particular,the spherical aberration tends to increase as the observation depth dincreases. Also, the light diameter of the observation light generatedat a deep position in the observation object B due to aberration(spherical aberration, astigmatism, coma aberration, defocus aberration,or the like) inside the observation object B is greater than the tightdiameter of the observation light generated at a shallow position (seeFIG. 5). Accordingly, as illustrated in FIG. 10(b), the point images P2of adjacent observation lights in the photodetector 41 overlap eachother according to the observation depth d and crosstalk may occur. Whencrosstalk occurs, it becomes difficult to accurately detect each of theplurality of observation lights L2.

On the other hand, in the image acquisition device 1A and the imageacquisition method of the present embodiment, as illustrated in FIGS. 2and 3, the center spacing W between adjacent light converging points P1is set on the basis of positions of a plurality of light convergingpoints P1 (that is, observation depths d) in the optical axis directionof the objective lens 32. Thereby, for example, when the light diameterof the point image P2 of the observation light in the photodetector 41is increased, the center spacing W between the light converging pointsP1 can be widened, so that it is possible to prevent the point images P2from overlapping each other and crosstalk can be reduced. Also, in theimage acquisition device 1A and the image acquisition method accordingto the present embodiment, the center spacing W between adjacent lightconverging points P1 is further set on the basis of the amounts ofaberration on the surface and/or the inside of the observation object B.Thereby, because the center spacing W between adjacent light convergingpoints P1 is set in consideration of the amounts of aberration on thesurface and/or the inside of the observation object B, it is possible tofurther suppress the overlapping of the plurality of point images P2 andreduce crosstalk. Accordingly, it is possible to accurately detect pointimages P2 of a plurality of observation lights and provide an image of aclear observation object.

Also, in the present embodiment, the plurality of light convergingpoints P1 refer to light converging points having the same amount oflight. For example, a light converging point where the amount of lightis significantly smaller than the other light converging points and doesnot contribute to image creation is not included in the light convergingpoints used here. In other words, the light converging point P1 in thepresent embodiment refers to a light converging point for generating theobservation light L2 useful for image creation.

Also, by forming a plurality of light converging points P1 using themodulating pattern to be presented in the spatial light modulator 13, itis possible to easily converge light on a desired position in adirection perpendicular or parallel to the optical axis direction of theirradiation light L1 and it is possible to easily change the number oflight converging points, a position, an intensity, and the like.

Also, as in the present embodiment, the computer 53 may increase thecenter spacing W as the plurality of light converging points P1 aredistanced further from the surface of the observation object B. Thereby,the crosstalk of the observation light caused by the aberration of thesurface of the observation object B can be suitably reduced.

Also, as in the present embodiment, the photodetector 41 has a pluralityof detection areas 45 for detecting the point images P2 of the pluralityof observation lights, and the sizes of the plurality of detection areas45 and a center spacing between the detection areas 45 may be set on thebasis of the positions of the plurality of light converging points P1 inthe direction of the optical axis of the objective lens 32. Thereby,because the pitch between and sizes of the plurality of detection areas45 are set according to the center spacing between the point images P2in the photodetector 41 and/or the light diameter, it is possible tosuitably detect the plurality of observation lights L2.

Also, as in the present embodiment, the photodetector 41 outputs aplurality of image data D1 corresponding to the plurality of detectionareas 45 as the detection signal Sd, and the computer 53 may create animage of the observation object B by combining a plurality of image dataD1 in the image generation step S8. Thereby, because it is possible todivide an area to be observed in the observation object B into aplurality of areas and create images of the areas in parallel, anobservation time can be effectively shortened.

Also, as in the present embodiment, the photodetector 41 may include amulti-anode photomultiplier tube having a plurality of anodes or mayinclude an area image sensor having a plurality of pixels. According toany one thereof, it is possible to accurately detect the light intensityof the observation light L2 in each of the plurality of point images P2.

Also, as in the present embodiment, a plurality of light convergingpoints P1 may be arranged in a direction intersecting the scanningdirection A2 when viewed from the optical axis direction of theobjective lens 32. Thereby, because it is possible to divide an area tobe observed in the observation object B into a plurality of areas andcreate images of the areas in parallel, an observation time can beeffectively shortened.

Also, in this embodiment, the modulating pattern to be presented on thespatial light modulator 13 may include an aberration correction patternfor the irradiation light L1. Thereby, it is possible to increase theresolution of measurement by reducing the size of the light convergingpoints P1. As a result, a wide observation area can be observed with asmall spacing. According to this embodiment, because a plurality oflight converging points P1 are simultaneously irradiated and pointimages P2 of a plurality of observation lights are simultaneouslydetected, the observation time can be effectively shortened and, forexample, it is possible to prevent an increase in the observation timeor to perform observation in a significantly short time even underconditions in which more observation time is required in observationwith a single light converging point P1.

First Modified Example

FIG. 11 is a flowchart of an image acquisition method according to afirst modified example of the above-described embodiment. An image at acertain observation depth d of the observation object B is acquired inthe above-described embodiment, but an image is obtained while theobservation depth d from the surface of the observation object B issequentially changed in the present modified example. Steps S1 to S8illustrated in FIG. 11 are the same as those in the above-describedembodiment and the description thereof will be omitted.

In this modified example, after the reference height Z0 of the objectivelens 32 is set (step S1), the computer 53 sets a plurality ofobservation depths d (step S11). The plurality of observation depths dmay be set by an observer via the input device 51 or may beautomatically set by the computer 53 on the basis of an imageacquisition range input by the observer.

Subsequently, as in the above-described embodiment, steps S2 to S8 areperformed. Thereafter, if no image has been prepared for all theobservation depths d (step S12: NO), the process returns to step S2again and the computer 53 resets the depth d of the light convergingpoint P1 to change the depth d. At this time, in step S3, the computer53 changes the center spacing W according to the change in theobservation depth d. Specifically, the computer 53 further widens thecenter spacing W when the light converging point P1 is further away fromthe surface of the observation object B. If an image has been createdfor all observation depths d (step S12: YES), the process is terminated.

As in the present modified example, the computer 53 may change thecenter spacing W in accordance with a change in positions of theplurality of light converging points P1 (i.e., observation depths d) inthe optical axis direction of the objective lens 32. Thereby,observation at a plurality of observation depths d can be continuouslyperformed while crosstalk is suppressed. In this case, the computer 53may increase the center spacing W as the plurality of light convergingpoints P1 are distanced further from the surface of the observationobject B. Thereby, the crosstalk of the observation light caused by theaberration of the surface of the observation object B can be suitablyreduced.

Second Modified Example

In the above-described embodiment, the light converging point P1 can bescanned by the light scanner 21. However, the light converging point P1may be scanned by moving the stage 31 in a plane direction intersectingthe optical axis direction. In other words, the scanning unit of theabove-described embodiment may include the stage 31 in place of thelight scanner 21 or together with the light scanner 21. Also in such aconfiguration, it is possible to suitably scan the light convergingpoint P1.

Third Modified Example

In the above-described embodiment, the light converging point P1 isscanned by the light scanner 21. However, a pattern (light scanninghologram) for scanning the light converging point P1 may be included(superimposed) in the modulating pattern to be presented on the spatiallight modulator 13. In this case, because the scanning unit in theabove-described embodiment is unnecessary, it is possible to reduce thenumber of components of the image acquisition device 1A and contributeto size reduction.

Example

Here, an example of the above-described embodiment will be described. Inthe present example, a resin containing a plurality of fluorescent beadseach having a diameter of 3 μm was prepared as the observation object B.This resin was observed using an objective lens (having 40 x waterimmersion and NA of 1.15). An image was acquired by forming a pluralityof light converging points P1 at a position of the depth d and scanningthe light converging points P1. At this time, the plurality of lightconverging points P1 was arranged in the direction A3 intersecting thescanning direction A2. Also, the observation depth d was 5 μm and 250μm. Also, in the following drawings, an arrow A4 of the drawingindicates a scanning start position of the plurality of light convergingpoints P1 in the direction A3.

FIG. 12 illustrates an obtained image when the observation depth d was5.68 μm as an optical distance and a center spacing W between the lightconverging points P1 was 13.7 μm. At this time, clear fluorescenceimages could be acquired.

Further, FIG. 13 illustrates an image obtained by setting theobservation depth d to 292 μm as an optical distance. FIG. 13(a) is animage obtained with the center spacing W of the plurality of lightconverging points P1 was set to 27.4 μm, and FIG. 13(b) is an obtainedimage when the center spacing W between the light converging points P1was 13.7 μm. As illustrated in FIG. 13(b), when the observation depth dwas changed to 292 μm and the center spacing W of 13.7 μm was notchanged, there was one fluorescent bead originally, but a plurality offluorescent beads appeared due to the influence of crosstalk of theobservation light (see a range B1 in FIG. 13(b)). On the other hand, asillustrated in FIG. 13(a), when the center spacing W was changed to 27.4μm on the basis of the observation depth d (292 μm), clear fluorescenceimages in which the influence of crosstalk was suppressed could beacquired.

INDUSTRIAL APPLICABILITY

It is possible to simultaneously radiate a plurality of lights for whichlight converging positions are different in a depth direction of anobservation object.

REFERENCE SIGNS LIST

-   -   1A Image acquisition device    -   10 Irradiation light generating unit    -   11 Light source    -   12 Beam expander    -   13 Spatial light modulator    -   14 Dichroic mirror    -   20 Scanning unit    -   21 Light scanner    -   22 Mirror    -   30 Irradiation optical unit    -   31 Stage    -   32 Objective lens    -   33 Objective lens moving mechanism    -   34 Reflection mirror    -   40 Observation unit    -   41 Photodetector    -   42 Filter    -   43 Condenser lens    -   44 Light detecting surface    -   44 a Light detecting unit    -   45 Detection area    -   50 Control unit    -   51 Input device    -   52 Display device    -   53 Computer    -   61, 62 Telecentric optical system    -   B Observation object    -   D1 Image data    -   L1 Irradiation light    -   L2 Observation light    -   P1 Light converging point    -   P2 Point image    -   Sd Detection signal

The invention claimed is:
 1. An image acquisition device comprising: aspatial light modulator configured to modulate irradiation light outputfrom a light source; a controller configured to control a modulatingpattern to be presented on the spatial light modulator so that aplurality of light converging points are formed in an observationobject; a lens configured to converge the modulated irradiation light sothat the plurality of light converging points are formed in theobservation object; a scanner configured to scan positions of theplurality of light converging points in the observation object in ascanning direction intersecting an optical axis of the lens; aphotodetector configured to detect a plurality of observation lightsgenerated from the plurality of light converging points; a telecentricoptical system provided on an optical axis of the irradiation light andthe observation light, the telecentric optical system configured totransfer a wavefront of the irradiation light generated in the spatiallight modulator to a rear focal point of the lens; and a dichroic mirrorarranged at a position at which the irradiation light modulated by thespatial light modulator and the observation light de-scanned by thescanner are received, wherein the controller is configured to set acenter spacing between adjacent light converging points on the basis ofthe positions of the plurality of light converging points in a directionof the optical axis of the lens, wherein the telecentric optical systemis a double-sided telecentric optical system and is adjusted to form animage on a modulation surface of the spatial light modulator and ascanning surface of the scanner, and wherein the dichroic mirrortransmits at least a part of the irradiation light, and reflects atleast a part of the observation light.
 2. The image acquisition deviceaccording to claim 1, wherein the controller is configured to change thecenter spacing according to a change in the positions of the pluralityof light converging points in the direction of the optical axis of thelens.
 3. The image acquisition device according to claim 2, wherein thecontroller is configured to increase the center spacing as the positionsof the plurality of light converging points in the direction of theoptical axis of the lens are distanced further from a surface of theobservation object.
 4. The image acquisition device according to claim1, wherein the scanner includes a light scanner configured to receivethe modulated irradiation light.
 5. The image acquisition deviceaccording to claim 1, wherein the scanner includes a stage configured tomove the observation object in the scanning direction while holding theobservation object.
 6. The image acquisition device according to claim1, wherein the photodetector has a plurality of detection areas fordetecting the plurality of observation lights, and wherein sizes of theplurality of detection areas and a center spacing between the detectionareas are set on the basis of the positions of the plurality of lightconverging points in the direction of the optical axis of the lens. 7.The image acquisition device according to claim 6, further comprising acomputer configured to create an image of the observation object using adetection signal from the photodetector, wherein the photodetector isconfigured to output a plurality of image data corresponding to theplurality of detection areas as the detection signal, and wherein thecomputer is configured to combine the plurality of image data to createthe image of the observation object.
 8. The image acquisition deviceaccording to claim 6, wherein the photodetector includes a multi-anodephotomultiplier tube having a plurality of anodes.
 9. The imageacquisition device according to claim 6, wherein the photodetectorincludes an area image sensor having a plurality of pixels.
 10. Theimage acquisition device according to claim 6, wherein the photodetectorincludes an avalanche photodiode array having a plurality of avalanchephotodiodes.
 11. The image acquisition device according to claim 1,wherein the plurality of light converging points are arranged in adirection intersecting the scanning direction when viewed from thedirection of the optical axis of the lens.
 12. The image acquisitiondevice according to claim 1, wherein the controller is configured to setthe center spacing between adjacent light converging points on the basisof amounts of aberration on a surface and/or an inside of theobservation object.
 13. An image acquisition device comprising: aspatial light modulator configured to modulate irradiation light outputfrom a light source; a controller configured to control a modulatingpattern to be presented on the spatial light modulator so that aplurality of light converging points are formed in an observationobject; a lens configured to converge the modulated irradiation light sothat the plurality of light converging points are formed in theobservation object; a photodetector configured to detect a plurality ofobservation lights generated from the plurality of light convergingpoints; a telecentric optical system provided on an optical axis of theirradiation light and an optical axis of the observation light, thetelecentric optical system configured to transfer a wavefront of theirradiation light generated in the spatial light modulator to a rearfocal point of the lens; and a dichroic mirror arranged at a position atwhich the irradiation light modulated by the spatial light modulator isreceived, wherein the modulating pattern includes a pattern for scanningthe plurality of light converging points in a scanning directionintersecting the optical axis of the irradiation light, wherein thecontroller is configured to set a center spacing between adjacent lightconverging points on the basis of positions of the plurality of lightconverging points in a direction of the optical axis of the irradiationlight, wherein the telecentric optical system is a double-sidedtelecentric optical system and is adjusted to form an image on amodulation surface of the spatial light modulator, and wherein thedichroic mirror transmits at least a part of the irradiation light, andreflects at least a part of the observation light.
 14. An imageacquisition method comprising: by a spatial light modulator, modulatingirradiation light output from a light source based on a modulatingpattern for forming a plurality of light converging points in anobservation object; converging the modulated irradiation light by a lensso that the plurality of light converging points are formed in theobservation object; scanning positions of the plurality of lightconverging points in the observation object in a scanning directionintersecting an optical axis of the irradiation light; detecting aplurality of observation lights generated from the plurality of lightconverging points while scanning the positions and generating adetection signal; and creating an image of the observation object basedon the detection signal, wherein a center spacing between adjacent lightconverging points is set on the basis of the positions of the pluralityof light converging points in a direction of the optical axis by themodulating, wherein a wavefront of the irradiation light is transferredby a double-sides telecentric optical system to a rear focal point ofthe lens, wherein at least a part of the irradiation light istransmitted by a dichroic mirror, and at least a part of the observationlight is reflected by the dichroic mirror.
 15. The image acquisitionmethod according to claim 14, wherein the center spacing is changedaccording to a change in the positions of the plurality of lightconverging points in the direction of the optical axis by themodulating.
 16. The image acquisition method according to claim 15,wherein the center spacing is increased as the positions of theplurality of light converging points in the direction of the opticalaxis are distanced further from a surface of the observation object bythe modulating.
 17. The image acquisition method according to claim 14,wherein the scanning is performed using a light scanner receiving themodulated irradiation light in the detecting.
 18. The image acquisitionmethod according to claim 14, wherein the scanning is performed using astage moving the observation object in the scanning direction whileholding the observation object in the detecting.
 19. The imageacquisition method according to claim 14, wherein the scanning isperformed using the spatial light modulator by modulating theirradiation light based on a pattern for scanning the plurality of lightconverging points superimposed on the modulating pattern in thedetecting.
 20. The image acquisition method according to claim 14,wherein a photodetector having a plurality of detection areas fordetecting the plurality of observation lights is used in the detecting,and wherein sizes of the plurality of detection areas and a centerspacing between the detection areas are set on the basis of thepositions of the plurality of light converging points in the directionof the optical axis.
 21. The image acquisition method according to claim20, wherein the photodetector is configured to output a plurality ofimage data corresponding to the plurality of detection areas as thedetection signal, and wherein the plurality of image data are combinedto create an image of the observation object in the creating.
 22. Theimage acquisition method according to claim 14, wherein the plurality ofthe observation lights are detected using a multi-anode photomultipliertube having a plurality of anodes in the detecting.
 23. The imageacquisition method according to claim 14, wherein the plurality of theobservation lights are detected using an area image sensor having aplurality of pixels in the detecting.
 24. The image acquisition methodaccording to claim 14, wherein the plurality of the observation lightsare detected using an avalanche photodiode array having a plurality ofavalanche photodiodes in the detecting.
 25. The image acquisition methodaccording to claim 14, wherein the plurality of light converging pointsare arranged in a direction intersecting the scanning direction whenviewed from the direction of the optical axis.
 26. The image acquisitionmethod according to claim 14, wherein the center spacing betweenadjacent light converging points is further set on the basis of amountsof aberration on a surface and/or an inside of the observation object.